• 한국철도학회논문집
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• 제6권2호
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• pp.81-86
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• 2003

This study proposes the neural network simulator for the integrity evaluation of weld zone in railway rails. For these purposes, the ultrasonic signals for defects(crack) of weld zone in frames are acquired in the type of time series data and echo strength. The detection of the natural defects in railway truck is performed using the characteristics of echodynamic pattern in ultrasonic signal. And then their applications evaluated feature extraction based on the time-frequency-attractor domain(peak to peak, rise time, rise slope, fall time, fall slope, pulse duration, power spectrum, and bandwidth) and attractor characteristics (fractal dimension and attractor quadrant) etc. The constructed neural network simulator agrees fairly well with the measured results of test block(defect location, beam propagation distance, echo strength, etc). The Proposed neural network simulator in this study can be used for the integrity evaluation of weld zone in railway rails.

• 한국안전학회지
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• 제32권6호
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• pp.131-136
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• 2017

This study deals with the small-size roundabout accidents. The purpose of this study is to analyze the characteristics of small-size roundabout accidents from developing various types of accident models, and to discuss the improvement countermeasures by vehicle type. The geometric characteristics of 36 roundabouts are surveyed, and the traffic accident data from 2008 to 2014 are collected and classified as those of car, truck and motor cycle. In this study, dependent variable is the number of accident and independent variables are such 15 variables as geometry and traffic volume. The main results are as follows. First, the null hypotheses that the size of roundabout and type of vehicle are not related to traffic accident are rejected. Second, 8 count data models which are all statistically significant are developed. Third, the number of circulatory roadway lane and sidewalk are selected as common variables of roundabout size. Finally, the number of entry and circulatory roadway lane are selected as common variables of vehicle type.

• 한국구조물진단유지관리공학회 논문집
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• 제14권4호
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• pp.148-153
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• 2010

각종 건설현장에서 구조재료로 사용되고 있는 콘크리트는 레미콘 공장에서 배합되어 레미콘 트럭에 의해 현장까지 운송 타설되는 형태로 공급되고 있다. 그러나 콘크리트가 현장까지 운송되는 동안 교통 체증, 기후 및 기타 여러 영향으로 인해 적정한 슬럼프의 유지가 곤란한 경우를 겪게 된다. 이럴 경우 콘크리트의 적정한 슬럼프 유지를 위해 혼화제를 첨가하게 된다. 그러나 실제 현장에 배달되는 레미콘의 경우는 트럭기사들이 레미콘을 쏟아 낼 때 슬럼프치가 부족하면 혼화제 대신 물을 추가로 넣어 비빈 후 타설을 하여 강도저하의 치명적 원인을 제공하는 경우가 발생되기도 한다. 이는 설계시 결정되어 모든 구조물 설계에 사용된 설계강도에 크게 미달하는 콘크리트 사용하게 됨으로써 추후 심각한 문제를 야기할 수 있다. 따라서 본 연구에서는 레미콘에 추가로 물을 첨가하는 문제를 해결하고자, 콘크리트에 현장에서 많이 사용되고 있는 혼화제를 정해진 시간간격으로 추가하는 것이 굳은 혹은 굳지 않은 콘크리트의 역학적 특성에 미치는 영향을 검토하여 콘크리트의 슬럼프 유지를 위한 적정한 혼화제 사용에 대한 근거자료를 제시하고자 한다.

• 한국전산구조공학회논문집
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• 제23권1호
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• pp.45-52
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• 2010

본 논문에서는 새로운 차량의 도입으로 건설되는 신형식 교량의 동적거동을 확인하기 위해 상용 유한요소 프로그램을 이용하여 해석을 실시하여 충격계수를 산정하였으며, 국내뿐만 아니라 각국에서 적용되고 있는 충격계수에 관한 설계기준을 조사하여 비교 검토하였다. 연구에서 제시되어진 교량형식은 파이프트러스 형식으로 각각 34m, 44m, 54m로 모델링하였으며 각각의 지간길이에 따른 충격계수의 영향을 산정하였다. 차량모델은 실제 교량 위를 통과하는 2축과 3축 저상굴절차량과 박영석(1997)이 제시한 147kN 덤프트럭 모델을 적용하였으며, 각 차량별로 10km/h~100km/h까지의 속도대역에 따른 충격계수를 산정하여 이에 따른 영향을 검토하였다. 또한 차량 및 지간길이에 따라 산정되어진 지간 중앙에서의 충격계수를 바탕으로 우리나라 및 외국의 설계규정과 비교 검토하였다.

• 한국산학기술학회논문지
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• 제20권5호
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• pp.510-519
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• 2019

본 연구에서는 보강토교대로 지지된 슬래브교의 설계 활하중을 도로교설계기준(2010)의 DB-24와 도로교설계기준(한계상태설계법)(2015)의 KL-510으로 구조해석을 수행하였다. 구조해석 결과로부터 산정된 슬래브교의 반력과 보강토교대에 작용하는 접지압에 대해 비교검토를 수행하였다. 교대에 작용되는 반력은 교각의 유무와 개수에 따라 다르게 산정되었다. 단경간에 비해 연속교에서 교대에 작용되는 반력이 감소되는 것으로 나타났다. 구조해석 결과, 활하중보다는 고정하중에 의한 반력이 약 2배 이상 크게 산정되었으며, 활하중이 전체 반력에 미치는 영향이 상대적으로 작았다. 보강토교대에 작용하는 접지압은 단경간에서 가장 크게 산정되었다. 이동하중의 종류에 따른 영향은 상대적으로 크지 않았다. 따라서, 연속교에서 교대에 작용되는 반력과 접지압이 작게 산정되기 때문에, 단경간 교량보다는 연속 교량에 보강토교대를 적용하는 것이 유리한 것으로 판단되었다. 보강토교대에 작용되는 반력과 하중 분담률은 다양한 조건에 따라 달라지므로, 다양한 교량 형식과 제원에서의 접지압 검토가 향후 필요하다.

• 한국농공학회논문집
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• 제62권4호
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• pp.87-97
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• 2020

The livestock infections had been happened seasonally, but they have gradually changed to be irrelevant to seasons and have an aspect to rapidly spread after outbreak. Especially in Korea, proactive disinfection measures are very important because the livestock farms are located densely so high as to accelerate the spread of disease between farms. livestock disease outbreaks like HPAI and FMD occurred with high probability due to vehicles visiting the farms, this study is to evaluate the efficiency of livestock vehicle disinfection systems by investigating the disinfectant coverage according to the type of vehicle disinfection system and the type of vehicle quantitatively. In field experiments, water-sensitive papers (WSPs) were attached to 21 locations on the surface of four vehicles (sedan, SUV, truck, and feed transport), respectively, and exposed to disinfectants while the vehicle was sprayed in two vehicle disinfection systems (tunnel type and simplified type). The WSPs were scanned and image-processed to calculate the disinfectant coverage. The results showed that the tunnel-type vehicle disinfection system had a better disinfection performance with an average coverage of 90.27% for all vehicles compared to 32.62% of the simplified type system. The problem of the simplified system was a wide coefficient of variation (1.05-1.31) of the disinfectant coverage between 21 locations indicating a need for further improvement of nozzle location and arrangement.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2011년도 춘계학술대회 논문집
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• pp.55-60
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• 2011

For the bolster type bogie, bolster anchor body connections are proviede to transmit the longitudinal loads for traction or braking between the carbody and the truck. The bolster anchor body connection is generally composed of anchor rod bracket, anchor rod and its fastening devices. The bolster anchor body connection shall be basically capable of withstanding a longitudinal load resulting from excessive braking case or impact. Additionally the north America standard requires that the anchor rod bracket shall be frangible, I.e. the anchor rod bracket shall fail and fall away under load before the carbody structure is damaged since to protect the cabody structure in the event of unexpected accident. This paper describes the shear connection design using the optimized mechanical fasteners in the bolster anchor body connection to satisfy these Northe America requirements.

• 한국생산제조학회지
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• 제21권2호
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• pp.344-348
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• 2012

The knuckle crane design in Korea has been performed by assuming a cantilever beam type structure and numerically analyzing design data and finally improving the stiffness by replacing material. In our study, a complete finite element model of the knuckle crane is constructed and finite element analysis is conducted using Optistruct. Structural optimization to reduce the weight of the knuckle crane is processed by applying maximum loading condition at the largest radius of motion, which is the worst case of loading condition. As the results, existing over stiff design in a knuckle crane is corrected to meet a desired design limit and overall weight is reduced, which eventually leads to a reduction of $CO_2$ emission.

• 한국생산제조학회지
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• 제20권4호
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• pp.458-463
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• 2011

A CHS(Container Handling System) is a system to load and to unload ISO 2000 or ISO 4000 standard containers which is widely used for various industrial transport purpose. A new light type of CHS is introduced in this paper, in order to reduce weight of cargos and to give the convenience in cargo loading and unloading without additional lifting equipments. The structural models of this system are created to assemble the smooth integration of system and to interface the each composing units with the specification of truck chassis to be mounted. These models are applied to find the suitable design parameters under the condition of force restrictions of each units. Finally, the stability of this system are investigated by analyzing the dynamic simulation using Visual NASTRAN 4D, and it could be recommend the good design parameters for the manufacturing purpose.

• Geomechanics and Engineering
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• 제3권1호
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• pp.45-59
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• 2011

Scaled centrifuge modelling techniques were used to study the soil-structure interactions and performance of a jointed rollable aluminium roadway (or trackway) system on soft clay under light truck tyre loads. The measured performance and subsequent analyses highlighted that the articulated connections significantly reduced the overall longitudinal flexural stiffness of the roadway leading to stress concentrations in the soil below the joints under tyred vehicle loadings. This resulted in rapid localised failure of the supporting soil that in turn led to excessive transverse flexure of the roadway and ultimately plastic deformations. It is shown that the performance of rollable roadway systems under tyred vehicle trafficking will be improved by eliminating joint rotation to increase longitudinal stiffness.